The UN chief has deplored Yemen's decision to expel the organisation's human rights representative in the country and called the government to reconsider its move.
Media reports in Yemen said on Thursday the country's foreign ministry had declared the head of the country office of the UN High Commissioner for Human Rights (OHCHR) persona non grata.
An AFP report identified the UN official as George Abu al-Zulof and said Yemen had accused him of lacking impartiality in his assessments of the human rights situation in the Arabian Peninsula country.
Ban Ki-moon, the UN secretary-general, said in a statement on Thursday that he had "full confidence" in Zulof and urged the Yemeni government "to reconsider its position on his expulsion", the news agency's report said.
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Earlier in the week, the OHCHR office in Yemen said that it had received allegations that Arab coalition forces used cluster bombs in attacks.
Ban said that respect for human rights was "absolutely essential" for Yemen's long-term peace and stability.
"By impeding the United Nations' human rights work, the government is failing to uphold its obligations. Doing so can only be harmful for the country's return to peace and stability," he said.
On Friday, the UN High Commissioner for Human Rights also called Yemen to reverse an "unwarranted, counter-productive and damaging" decision to expel his representative.
"Our job is not to highlight violations committed by one side and ignore those committed by the other," said Zeid Ra'ad Al Hussein.
"I fear it will hamper our work in the future."
Air strikes by the Arab coalition assembled by Saudi Arabia have intensified since the humanitarian ceasefire in Yemen ended on January 2.
Iran-allied Houthi fighters have accused the coalition of using cluster bombs, an internationally banned weapon, during an attack in the western part of the capital Sanaa on Wednesday.
The attack left one person dead and many injured.
For its part, the Arab coalition has accused Houthi fighters and their allies of firing ballistic missiles towards Saudi cities and border posts, as well as hampering aid operations in Yemen.
"All this shows their lack of seriousness and disregard for civilian lives as well as their attempt to take advantage of the truce to achieve gains," it said in a statement late last month.
The destructive nature of cluster bombs led to the adoption of the Convention on Cluster Munitions in Oslo in 2008.
Human Rights Watch, the New York-based organisation, says a total of 118 countries have signed and 98 have ratified the Oslo treaty, but neither Yemen, Saudi Arabia, nor any of the other coalition countries is party to it.
Human Rights Watch, which is a co-founder of the Cluster Munition Coalition and serves as its chair, has asked the the UN Human Rights Council to create an independent, international inquiry into alleged violations of the laws of war by all sides.
Source: Al Jazeera and agencies